1 3 4 BACTERIOLOGY. 



sometimes broken up into irregular segments or 

 granules, as in many spirilla, and we may perhaps 

 add the bacilli of tuberculosis and leprosy. The 

 beaded appearance of the tubercle bacillus is well 

 known. Some observers have regarded the beads, 

 others the bright spaces between them, as spores. 

 But spores in unstained preparations appear as 

 glistening bodies with sharp contour, and do not 

 stain at all, or very little, by the ordinary processes. 

 It appears, therefore, very doubtful whether either 

 the clear spaces or the beads are spores, espe- 

 cially as the tubercle bacillus, when unstained, 

 is a slightly curved hyaline rod, without any dif- 

 ferentiation into granules. These considerations 

 led the author to stain and examine tubercular 

 sputum from various sources under careful 

 illumination, and with such lenses as Powell and 

 Lealand's -^ in. Horn. imm. The tubercle bacillus 

 may then be frequently seen to consist of a very 

 delicate sheath, holding together a number of 

 deeply-stained granules, for the most part round 

 or cylindrical, with irregular contour, and differing 

 considerably in size, while the light interspaces 

 are seen to vary in form according to the shape 

 of the granules. In some preparations more dis- 

 tinct, and clearly ovoid, granules may be observed 

 which are sometimes terminal. They can be readily 

 demonstrated by taking a photograph with a ^5 in. 

 Horn, imm., and subsequently enlarging the nega- 

 tive to from 2,500 (Fig. 58) to 6,000 diameters. 



